1. Field of the Invention
The present invention relates generally to wireless communication devices, and more particularly, to such a wireless communication device including a Subscriber Identity Module.
2. Background Art
A Subscriber Identity Module (SIM) is a smart card, or the like, used in connection with a Wireless Communication Device (WCD), such as a cellular radiotelephone, for example. A conventional SIM includes a small computer system having a controller and a memory. The SIM memory contains information related to a subscriber/user of the WCD, including, for example, a subscriber/user identifier, a phonebook identifying a stored bank of telephone numbers, messages, encryption sequences for secured data communications over the air, and so on. Typically, a subscriber can install the SIM in or remove the SIM from the WCD. The SIM can be removed from a first WCD and installed in a second WCD, thereby allowing the user the flexibility of being able to essentially transport his or her “identity” between WCDs.
A conventional SIM includes a relatively simple electrical interface, including a SIM I/O port for transmitting serialized data to and receiving serialized data from another device (such as a WCD), a SIM clock input for receiving a clock, and reset input for receiving a reset signal. However, functionally interfacing with the conventional SIM (for example, interacting with and accessing data from the SIM) can be complicated because the SIM has a processor, and because there are various existing standards (such as the Global System for Mobile Communications (GSM) standards) generally requiring a relatively elaborate scheme for communicating with a SIM. Therefore, functionally interfacing with the SIM through a functional SIM interface is more complicated than just reading data from a memory, for example. Instead, the SIM and a requesting device connected thereto (for example, the WCD) actually exchange commands and responses in a back-and-forth fashion. Further complicating matters is the fact that some SIMs do not comply with generally accepted SIM interface standards (such as GSM).
Therefore, there is a need to provide an interface for interfacing a WCD to a SIM both electrically and functionally, whereby the WCD can control and access the information contained in the SIM. There is a related need to provide such an interface enabling a WCD to interface with a SIM that complies with generally accepted SIM interface standards, and a SIM that does not comply with such standards.
There is an ever increasing need to reduce power consumption in, and a part count, size, and cost of a WCD. Therefore, it is desirable to reduce all of these aspects in a WCD including an interface for interfacing the WCD to a SIM.